| 摘要 |
A discharge lamp lighting device for AC lighting has PT(21), CT1(22), a fluctuation detection circuit (28), and a control circuit (36). PT(21) detects a voltage to be supplied to a HID bulb (5) and CT1(22) detects a current to be supplied to the HID bulb (5). The fluctuation detection circuit (28) generates an output power equivalent value obtained by adding each voltage value corresponding to each detected value by PT(21) and CT1(22), and outputs the fluctuation signal corresponding to the change of the output power equivalent value. The control circuit (36) changes a duty ratio of a control signal to be supplied to the switching transistor (6) according to the fluctuation signal.
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